Localisation issue

Localisation issue

Hi guys,
Thank you very much for this excellent picker. I use it in an ext js 4 application, which I have localized in the greek language (see the localisation file). I figured out, that the picker without localisation works perfectly. Note that I have chosen the format 'F, Y' for the picker. With the localisation, I pick a month-year, the picker selects the correct month-year, and when I click out of the picker, the year remains correct but the month changes to its original value. Now I use the format 'm/Y' that works. I noticed that
if I comment out the line: monthNames : Ext.Date.monthNames,
in the ext-lang-el_GR.js file, it works ok, showing the months in English.
if(Ext.picker.Date){
Ext.apply(Ext.picker.Date.prototype, {
todayText : "Σήμερα",
minText : "Η Ημερομηνία είναι προγενέστερη από την παλαιότερη αποδεκτή",
maxText : "Η Ημερομηνία είναι μεταγενέστερη από την νεότερη αποδεκτή",
disabledDaysText : "",
disabledDatesText : "",
monthNames : Ext.Date.monthNames,
dayNames : Ext.Date.dayNames,
nextText : 'Επόμενος Μήνας (Control+Δεξί Βέλος)',
prevText : 'Προηγούμενος Μήνας (Control + Αριστερό Βέλος)',
monthYearText : 'Επιλογή Μηνός (Control + Επάνω/Κάτω Βέλος για μεταβολή ετών)',
todayTip : "{0} (ΠΛήκτρο Διαστήματος)",
format : "d/m/y"
});
}

I also tried to change a format of a normal datepicker, to 'F, Y'. That is, I chose a date and the result was ok, (month Year). When I clicked out of the datepicker, the values remained unchanged.
Thanks in advance,
Harry